Design of unsymmetric coumarin chalcone derivatives with tunable self-assembling behavior

Abstract

Unsymmetric coumarin chalcone derivatives were designed with unsymmetric alkoxy chain on both terminal of the molecules to find their effect on the overall mesomorphic properties. In the first homologous series, compounds with fixed octyloxy chain on chalcone end and varied alkoxy chain length at coumarin end of the molecule (n = 10,12,14,16,18) have been analyzed for their mesomorphic properties. In this series, all the Compounds showed stable enantiotropic SmC mesophase. In the second homologous series, compounds with fixed octyloxy chain on coumarin end and varied alkoxy chain length at chalcone end (n = 10,12,14,16,18) have been studied for their mesomorphic properties. In the second homologues series, compounds (n = 10,12) exhibited monotropic nematic mesophase. For higher analogues (n = 16,18), enantiotropic SmA mesophase was observed. Further, the powder X-ray diffraction analysis of the three compounds from both the series at 112 °C showed diffraction pattern quite close to identified mesophase type. To understand effect of variation of terminal chain, DFT theoretical study was carried out for both different series and tried to understand correlation between mesomorphic properties and structural parameters.